✔ 最佳答案
Method 1 :
Sum of the roots :
(-2) + 3 = -b
b = -1
Product of the roots :
(-2) × 3 = c
c = -6
Method 2 :
x = -2 or x = 3
(x + 2) = 0 or (x - 3) = 0
(x + 2)(x - 3) = 0
x² - x - 6 = 0
Compare the equation (x² - x - 6 = 0) with the equation (x² + bx + c = 0)
b = -1 and c = -6
Method 3 :
Sub. x = -2 into the given equation :
(-2)² + (-2)b + c = 0
-2b + c = -4 ...... [1]
Sub. x = 3 into the given equation :
(3)² + (3)b + c = 0
3b + c = -9 ...... [2]
[2] - [1] :
5b = -5
b = -1
Sub. b = -1 into [1] :
-2(-1) + c = -4
c = -6